# Trailer Securement Ledger — data dictionary

**Version 1.2.0 · Verified 17 September 2026**

The six data tables contain 108 records: 30 authority, 19 timeline, 15 restraint, 12 chock/guide, 14 manufacturer-instruction and 18 exception records. The chock table contains six products plus six selected guide weight bands. This is a purposive reference compilation, not a statistical sample of the market or a facility approval.

## Types, keys and missing values

All CSV values are text; numeric fields become JSON numbers and empty fields become JSON `null`. Boolean-like descriptive fields remain text because their qualifications matter. The JSON `tables` objects contain every CSV row and column. Record keys are `id` within each table and `seq` in the timeline. Never treat a blank, not-stated rating, or non-applicable RIG field as zero or unlimited capability.

Manufacturer inputs are source-reported, not independently tested. `vertical_window_span_in` and explicit unit conversions are calculated. Editorial fields are identified below and must not be passed off as issuer findings. A JSON null minimum guard clearance means the cited clauses specify no minimum; it is not a legal zero baseline.

## Fields by table

### trailer-securement-authority-ledger.csv

| Field | JSON type when present | Definition / unit / scope |
|---|---|---|
| `id` | string | Stable ID within its table. A=authority, R=restraint, C=chock/guide, M=manufacturer, E=exception. Do not join tables on the prefix-free number. |
| `jurisdiction` | string | Legal geographic scope (for example US federal or California); not automatic application to every employer. |
| `instrument_type` | string | Regulation, interpretation, directive, publisher preview or other authority class; these do not have equal legal effect. |
| `citation` | string | Exact regulation, clause, document or public-standard identifier supporting the record. |
| `subject` | string | The narrow regulatory or reference subject, not a facility compliance classification. |
| `edition_or_date` | string | Regulatory vintage, issue date or inspected edition. “Current as read” means verified on verified_date, not a new publication date. |
| `status_as_read` | string | Document’s substantive status and scope as established in cited material. Historical rows may be withdrawn/superseded; read scope_note. |
| `who_it_applies_to` | string | Covered employer, operation or vehicle population and any named exclusions. |
| `plain_english_requirement` | string | Original short paraphrase of the cited material; not verbatim law and not a complete facility determination. |
| `names_wheel_chocks` | string | Descriptive text explaining whether the quoted provision names chocks/blocks; not a yes/no permission-to-load result. |
| `text_itself_allows_a_restraint` | string | Descriptive distinction between the instrument’s text and a separate enforcement alternative; keep scope and jurisdiction. |
| `source_url` | string | Issuer source for this record. An earlier event may be documented in a later primary issuer history. |
| `verified_date` | string | ISO date of actual content verification for this release: 2026-09-17. Not deployment or underlying publication date. |
| `evidence_type` | string | Source-reported, calculated input/span, or source-grounded editorial synthesis as named. Does not mean independent testing. |
| `claim_type` | string | Verification class: primary-source required, current-verification required, editorial judgment, or an explicit combination. |
| `publish_status` | string | Publication gate and scope. Publishable means support exists within the stated scope, not equipment approval. |
| `source_locator` | string | Exact clause, PDF printed page, document section, feature heading or other supporting location. |
| `verification_method` | string | Method used to establish content; direct page fetch and issuer-indexed extract are not identical. Private audit notes list access limitations. |
| `scope_note` | string | Consequential applicability, comparability, unit, model, date or missing-value limitation; do not detach it from the record. |
| `additional_source_urls` | string | Other relevant issuer URLs separated by space-pipe-space. May be empty. |

### trailer-securement-policy-timeline.csv

| Field | JSON type when present | Definition / unit / scope |
|---|---|---|
| `seq` | number | Integer timeline sequence; stable key for these 19 historical records. |
| `date` | string | Historical event/document date, ISO where established. A year-only date is intentionally less precise; conflicts are recorded in scope_note. |
| `document` | string | Source document name; manufacturer instructions apply to this named document/model. |
| `doc_type` | string | Historical instrument class, not current legal effect. |
| `issuer` | string | Body that issued the historical material; not Uptime. |
| `what_it_did` | string | Original factual paraphrase of the event or instrument, with limits in scope_note. |
| `status_as_read` | string | Document’s substantive status and scope as established in cited material. Historical rows may be withdrawn/superseded; read scope_note. |
| `source_url` | string | Issuer source for this record. An earlier event may be documented in a later primary issuer history. |
| `verified_date` | string | ISO date of actual content verification for this release: 2026-09-17. Not deployment or underlying publication date. |
| `claim_type` | string | Verification class: primary-source required, current-verification required, editorial judgment, or an explicit combination. |
| `evidence_type` | string | Source-reported, calculated input/span, or source-grounded editorial synthesis as named. Does not mean independent testing. |
| `publish_status` | string | Publication gate and scope. Publishable means support exists within the stated scope, not equipment approval. |
| `source_locator` | string | Exact clause, PDF printed page, document section, feature heading or other supporting location. |
| `scope_note` | string | Consequential applicability, comparability, unit, model, date or missing-value limitation; do not detach it from the record. |
| `additional_source_urls` | string | Other relevant issuer URLs separated by space-pipe-space. May be empty. |

### trailer-securement-restraint-specs.csv

| Field | JSON type when present | Definition / unit / scope |
|---|---|---|
| `manufacturer` | string | Issuer brand/company for the named restraint or instructions; not independent verifier. |
| `model` | string | Exact named model/configuration. For selected guide bands, this field is a reference label, not a second product model. |
| `device_family` | string | Engagement family: RIG-dependent or wheel-dependent. Manual/powered actuation and monitoring are separate. |
| `engagement_method` | string | What the named device engages/how it is described in the cited source. |
| `power_type` | string | Named-model actuation description; not implied by engagement family. |
| `published_restraining_force_lb` | number | Printed manufacturer restraint-force number in pounds-force. Keep force_qualifier and force_wording_as_published; no comparable release threshold is inferred. |
| `force_wording_as_published` | string | Source wording/short paraphrase retaining meaning and qualifiers; numerical value is not independent test data. |
| `vertical_window_low_in` | number | Published lower guard-height engagement endpoint above the driveway, inches, for the named RIG configuration. |
| `vertical_window_high_in` | number | Published upper guard-height engagement endpoint above the driveway, inches. |
| `vertical_window_span_in` | number | Calculated high endpoint minus low endpoint, inches. This is arithmetic span, not measured dynamic travel, a legal height interval or a complete fit test. |
| `horizontal_reach_in` | number | Published horizontal reach/end of service range, inches; origin/configuration varies. PowerHook/PowerStop descriptions specify ranges starting at zero. Not Serco rear-axle position. |
| `stated_min_contact_height_in` | number | Manufacturer minimum contact-space figure in inches when verified; not the guard’s regulatory cross-sectional height. |
| `nameplate_or_certification_note` | string | Exact context for an illustrated nameplate or manufacturer conformity statement. No independent certification body or test protocol is inferred. |
| `source_document` | string | Exact source title, part number, revision or identifier when available. |
| `source_url` | string | Issuer source for this record. An earlier event may be documented in a later primary issuer history. |
| `document_date` | string | Actual source date/revision, or explicitly undated; never inferred from a URL upload folder. |
| `verified_date` | string | ISO date of actual content verification for this release: 2026-09-17. Not deployment or underlying publication date. |
| `evidence_type` | string | Source-reported, calculated input/span, or source-grounded editorial synthesis as named. Does not mean independent testing. |
| `id` | string | Stable ID within its table. A=authority, R=restraint, C=chock/guide, M=manufacturer, E=exception. Do not join tables on the prefix-free number. |
| `force_qualifier` | string | Preserves distinctions such as “up to”, “in excess of”, stated capacity, or not reported. Do not average unlike qualifiers. |
| `scope_note` | string | Consequential applicability, comparability, unit, model, date or missing-value limitation; do not detach it from the record. |
| `source_locator` | string | Exact clause, PDF printed page, document section, feature heading or other supporting location. |
| `claim_type` | string | Verification class: primary-source required, current-verification required, editorial judgment, or an explicit combination. |
| `publish_status` | string | Publication gate and scope. Publishable means support exists within the stated scope, not equipment approval. |
| `wheel_capture_low_in` | number | Serco SLSC rear-axle position lower endpoint measured from dock face, inches. Different from vertical RIG height and hook reach. |
| `wheel_capture_high_in` | number | Serco SLSC rear-axle position upper endpoint from dock face, inches; 14 ft × 12 = 168 in (calculated conversion). |

### trailer-securement-chock-ratings.csv

| Field | JSON type when present | Definition / unit / scope |
|---|---|---|
| `brand` | string | Chock issuer brand. |
| `model` | string | Exact named model/configuration. For selected guide bands, this field is a reference label, not a second product model. |
| `material` | string | Manufacturer-stated material, with HDPE distinguished from polyurethane. |
| `length_in` | number | Published product length in inches, named model; not application clearances. |
| `width_in` | number | Published product width in inches. |
| `height_in` | number | Published product height in inches. |
| `weight_lb` | number | Product’s own published weight in pounds when retained; NOT GVW, payload or holding force. |
| `published_rating_type` | string | What the product/guide actually rates (gross vehicle operating weight, selected guide band, etc.). |
| `published_rating_value` | string | Source-reported rating and conditions in text; do not convert payload into GVW. |
| `max_tire_diameter_in` | number | Named-product maximum tire diameter in inches when stated. Blank does not mean unlimited. |
| `published_grade_limit_pct` | number | Named-product slope limit expressed as percent grade, not degrees. Null when not stated on that page. |
| `rating_is_a_holding_force` | string | Descriptive assessment of the cited rating: vehicle-weight/application ratings are not measured pull-out forces. |
| `what_the_rating_does_not_tell_you` | string | Uptime editorial limitation on interpreting the manufacturer rating. |
| `source_url` | string | Issuer source for this record. An earlier event may be documented in a later primary issuer history. |
| `verified_date` | string | ISO date of actual content verification for this release: 2026-09-17. Not deployment or underlying publication date. |
| `evidence_type` | string | Source-reported, calculated input/span, or source-grounded editorial synthesis as named. Does not mean independent testing. |
| `id` | string | Stable ID within its table. A=authority, R=restraint, C=chock/guide, M=manufacturer, E=exception. Do not join tables on the prefix-free number. |
| `record_type` | string | product for six named products; selected_guide_weight_band for six selected guide bands. Do not count guide bands as more products. |
| `document_edition` | string | Manual revision/date or guide identifier; includes current page verification if undated. |
| `source_locator` | string | Exact clause, PDF printed page, document section, feature heading or other supporting location. |
| `gross_vehicle_operating_weight_lb` | number | Named-product gross vehicle operating weight rating in pounds; not a pull-out force or payload. |
| `payload_capacity_as_reported` | string | Separate manufacturer payload statement (70-ton or 400-ton wording retained). It is not a conversion of gross vehicle weight. |
| `guide_test_grade_pct` | number | 8% chart test basis in the cited 2025 Checkers guide for the selected guide records; not a universal product operating limit. |
| `quantity_condition` | string | Number-of-chocks/application condition. MC3011 requires minimum four chocks at 855,000–1,600,000 lb. |
| `scope_note` | string | Consequential applicability, comparability, unit, model, date or missing-value limitation; do not detach it from the record. |
| `claim_type` | string | Verification class: primary-source required, current-verification required, editorial judgment, or an explicit combination. |
| `publish_status` | string | Publication gate and scope. Publishable means support exists within the stated scope, not equipment approval. |

### trailer-securement-manufacturer-instructions.csv

| Field | JSON type when present | Definition / unit / scope |
|---|---|---|
| `id` | string | Stable ID within its table. A=authority, R=restraint, C=chock/guide, M=manufacturer, E=exception. Do not join tables on the prefix-free number. |
| `manufacturer` | string | Issuer brand/company for the named restraint or instructions; not independent verifier. |
| `document` | string | Source document name; manufacturer instructions apply to this named document/model. |
| `document_edition` | string | Manual revision/date or guide identifier; includes current page verification if undated. |
| `section` | string | Exact location within the named manufacturer document. |
| `what_the_manufacturer_says` | string | Short quotation/paraphrase of the named source. Not a generalized operating or bypass procedure. |
| `why_it_matters_for_the_chock_question` | string | Uptime editorial interpretation, distinct from the manufacturer-reported column. |
| `source_url` | string | Issuer source for this record. An earlier event may be documented in a later primary issuer history. |
| `verified_date` | string | ISO date of actual content verification for this release: 2026-09-17. Not deployment or underlying publication date. |
| `evidence_type` | string | Source-reported, calculated input/span, or source-grounded editorial synthesis as named. Does not mean independent testing. |
| `claim_type` | string | Verification class: primary-source required, current-verification required, editorial judgment, or an explicit combination. |
| `publish_status` | string | Publication gate and scope. Publishable means support exists within the stated scope, not equipment approval. |
| `editorial_column_type` | string | Explicit identification of the editorial interpretation field. |

### trailer-securement-exceptions.csv

| Field | JSON type when present | Definition / unit / scope |
|---|---|---|
| `id` | string | Stable ID within its table. A=authority, R=restraint, C=chock/guide, M=manufacturer, E=exception. Do not join tables on the prefix-free number. |
| `condition` | string | Vehicle, guard, installation or operating condition requiring a check; not automatic incompatibility or illegality. |
| `category` | string | Type of scope/compatibility question; exceptions apply only within cited definitions. |
| `why_a_rig_restraint_may_not_engage` | string | Source-grounded editorial implication. Not an agency compatibility finding, loading permission or instruction to bypass. |
| `authority_or_source` | string | Issuer/source category for the exception record. |
| `citation_or_url` | string | Original citation/reference label; the fully linked primary URL is in source_url. |
| `verified_date` | string | ISO date of actual content verification for this release: 2026-09-17. Not deployment or underlying publication date. |
| `evidence_type` | string | Source-reported, calculated input/span, or source-grounded editorial synthesis as named. Does not mean independent testing. |
| `source_url` | string | Issuer source for this record. An earlier event may be documented in a later primary issuer history. |
| `additional_source_urls` | string | Other relevant issuer URLs separated by space-pipe-space. May be empty. |
| `source_locator` | string | Exact clause, PDF printed page, document section, feature heading or other supporting location. |
| `claim_type` | string | Verification class: primary-source required, current-verification required, editorial judgment, or an explicit combination. |
| `publish_status` | string | Publication gate and scope. Publishable means support exists within the stated scope, not equipment approval. |
| `scope_note` | string | Consequential applicability, comparability, unit, model, date or missing-value limitation; do not detach it from the record. |

## Source-manifest fields

`source_id`: local manifest identifier; `source_url`: issuer URL; `publisher_host`: source host; `used_by`: table keys or article-only use; `exact_locations`: supporting clause/page/section references; `editions_or_periods`: underlying source vintages; `verified_date`: actual check date; `verification_scope`: access and interpretation scope; `rights_note`: no third-party license assignment. The manifest is an index, not additional data observations.

## Reproducing the calculations

Run `python build-trailer-securement-ledger.py --directory .` to rebuild the complete JSON. Run the same command with `--check` to validate it without changing it. The script uses Python 3.10+ and the standard library only. It does not fetch web content or claim that a later rebuild re-verifies source facts.

- **vertical_window_span_in:** published high endpoint - published low endpoint; arithmetic span, not measured travel.
- **mean_vertical_window_span_in:** sum of 13 complete arithmetic spans / 13.
- **count_windows_starting_at_or_below_9_in:** count complete rows with low endpoint <= 9 in.
- **count_windows_ending_below_30_in:** count complete rows with high endpoint < 30 in; not a legal fit result.
- **nameplate_example_load_kN:** 22500 lbf * 4.448222 N/lbf / 1000 N/kN.
- **R15_wheel_capture_high_in:** 14 ft * 12 in/ft = 168 in; rear-axle position from dock face, not a RIG window.
- **R01_reach_conversion_check_mm:** 14 in * 25.4 mm/in = 355.6 mm; manufacturer prints 381 mm beside 14 in; unresolved source unit inconsistency.

The force summary reports which printed numbers appear and how many named records contain one. It deliberately has no force average or comparable-capacity range. The arithmetic mean span is 244.5 in / 13 = 18.81 in rounded; it is not a performance score. The 22,500 lbf example converts to 100.084995 kN, rounded to 100.1 kN, using NIST’s published 4.448222 N/lbf factor.

## Reuse and limitations

The compilation contains original selection, short factual paraphrases and editorial interpretation. Source owners retain their rights. No new open license is assigned to their documents, standards, diagrams or full tables. The files do not reproduce the paid MH30.3 or J348 text, manufacturer placards or the complete Checkers selection chart. Source-reported model values apply only to the cited configuration/document; installation, operating safety and legal applicability still need the actual facts and instructions.